COMPARATIVE INVITRO AND INVIVO SUSCEPTIBILITIES OF THE LYME-DISEASE SPIROCHETE BORRELIA-BURGDORFERI TO CEFUROXIME AND OTHER ANTIMICROBIAL AGENTS

The in vitro and in vivo susceptibilities of the Lyme disease pathogen Borrelia burgdorferi to cefuroxime were compared with those of several other antibiotics commonly used to treat this disease. Cefuroxime demonstrated a higher MBC in vitro (1.0 μg/ml) than ceftriaxone (0.08 μg/ml) or erythromycin (0.32 μg/ml), but the MBC was similar to that of amoxicillin (0.8 μg/ml) and doxycycline (1.6 μg/ml). B. burgdorferi was considerably less susceptible to tetracycline (3.2 μg/ml) and penicillin G (6.4 μg/ml). Of the three other Borrelia species tested, two (Borrelia turicatae and Borrelia anserina) also demonstrated susceptibility to cefuroxime, while the third (Borrelia hermsii) was less susceptible. Results obtained with four antimicrobial agents in the in vivo hamster model parallel the antibiotic susceptibilities in the in vitro study. The three antibiotics with similar MBCs in vitro, i.e., cefuroxime, doxycycline, and amoxicillin, demonstrated comparable activities in preventing borreliosis in B. burgdorferi-challenged hamsters (50% curative doses = 28.6, 36.5 and 45.0 mg/kg, respectively). Penicillin G, which demonstrated the highest MBC in vitro, had very weak protective activity in the hamster model system. These results indicate that the in vitro and in vivo activities of cefuroxime against B. burgdorferi are comparable to those of several oral antibiotics currently being used in the treatment of early Lyme disease and suggest that the oral form of this cephalosporin may be an effective alternative therapy for this disease.